As in think about something other than the latest movie, cell phone app, or trashy, vacuous trend.
Materials to support such thinking activities (hence speaking) are notoriously lacking even in regards to sources in their native language.
In an effort to avoid spending more money for my own textbooks (my company - POSEF - can not apparently afford to purchase a few meager learning materials, much less text books for its students much less the teachers.), I searched and found some sample question sites online.
English Club : includes actual audio file samples and transcripts in case the audio files flunk out on you.
TOEFL HELPDESK : Nice lengthy list of speaking topics.
Internet TESL Journal : HUGE selection of questions arranged by category. Not necessarily TOEFL related.
English-Test.net : sub-forum concerning the TOEFL test. Nice wealth of material, but you need to search through to find speaking-related posts.
Thanks again for stopping into my little corner of the 'net, and Happy Browsing!!